Abstract

Nanofibrillated cellulose (NFC) was systematically tailored by ultrasonic-assisted esterification with lactic acid at different amplitudes and times, which led to modified NFC (mNFC) with different degrees of substitution (DS), between 0.21 and 0.55, as confirmed by titration, FTIR, and C¹³ NMR. A partial fragmentation and decrease in crystallinity of mNFC were revealed by TEM and XRD. To form molded pulp sheets, 5 wt% mNFC was added into a bagasse (BG) pulp slurry, then partially dewatered before hot-pressed. mNFC worked effectively as self-retention aid, partly solving the issue of drainage during sheet forming as commonly observed from unmodified NFC. The BG/mNFC (DS 0.55) sheet exhibited an enhancement in tensile properties. Water resistance and barrier performance of the current sheets were also evidently increased. The results suggested that the higher DS on mNFC can improve water resistance and mechanical properties, simultaneously overcoming drainage challenges in processing of molded pulp products.

摘要

纳米原纤化纤维素 (NFC) 通过在不同振幅和时间下与乳酸的超声辅助酯化作用系统地定制，这导致改性 NFC (mNFC) 具有不同的取代度 (DS)，在 0.21 和 0.55 之间，如滴定、FTIR 所证实和 C ¹³ NMR。TEM 和 XRD 揭示了 mNFC 的部分破碎和结晶度降低。为了形成模塑浆板，将 5 重量％的mNFC 添加到甘蔗渣( BG ) 中果肉浆，然后在热压前部分脱水。mNFC 作为自留辅助剂有效地发挥了作用，部分解决了片材成型过程中的排水问题，如未改性 NFC 常见的那样。BG/mNFC (DS 0.55) 片材表现出拉伸性能的增强。电流片的耐水性和阻隔性能也明显提高。结果表明，mNFC 上更高的 DS 可以提高耐水性和机械性能，同时克服模塑纸浆产品加工过程中的排水挑战。